Can you Open Support Ticket and Compress (ZIP or RAR) your c:\Users\<UserName>\AppData\Roaming\MediaMonkey\LastFM_Cache.dat ?

I am getting this same issue, when playing a track it will show on last.fm as now playing, but it will never submit the play. I get the error:
Last.FM: Cache Submission Failed Plugin bug: Not all request variables are set - got 452 parameters.

I uninstalled and reinstalled the last.fm plugin, cleared the cache, etc. and I'm still getting the same behavior: now playing shows fine, log shows:

[code]11/14/2011 13:03:22.657: Last.FM: Cache Submit Failed Plugin bug: Not all request variables are set - got 101 parameters.
11/14/2011 13:03:22.678: Last.FM: Cache Submission Failed Plugin bug: Not all request variables are set - got 101 parameters.[/code]

Any ideas? (This started happening when I installed one of the recent RC builds and my settings and preferences were also frustratingly clobbered by the MM install.)

Since the other day, scrobbling just stopped working. Tracks are starting to build up in the cache and are erroring out on submit to last.fm (though the "Now Playing" works fine, tracks never actually get scrobbled).

I'm using build 1459 with the latest last.fm plugin.

Here's a relevant portion of the log, where it chokes while submitting cached songs:

[code]11/11/2011 14:22:17.373: Last.FM: Player got Command wParam (Play Counter)
11/11/2011 14:22:17.425: Last.FM: Submit Started at 1321039337
11/11/2011 14:22:17.434: Last.FM: Session ID d566e8fe580e475f9f80d9976b321452
11/11/2011 14:22:17.480: Last.FM: Player got Command wParam (Status)
11/11/2011 14:22:17.944: Last.FM: Cache Submit Started
11/11/2011 14:22:18.093: Last.FM: Cache Submit URL http://post2.audioscrobbler.com:80/protocol_1.2?s=d566e8fe580e475f9f80d9976b321452&a[0]=Roy Shirley with The Caltone Studio Orchestra&t[0]=Get On The Ball&i[0]=1320704058&o[0]=P&r[0]=&l[0]=193&b[0]=Caltone R%26B TONE 101&n[0]=Caltone R&B TONE 101&m[0]=&a[1]=Czerwone Gitary&t[1]=Kwiaty We Wlosach&i[1]=1320704189&o[1]=P&r[1]=&l[1]=134&b[1]=O Milosci&n[1]=16&m[1]=&a[2]=Godfather Don&t[2]=Involuntary Excellence&i[2]=1320704471&o[2]=P&r[2]=&l[2]=284&b[2]=Hazardous&n[2]=10&m[2]=&a[3]=William Basinski&t[3]=D|P 5&i[3]=1320940735&o[3]=P&r[3]=&l[3]=3140&b[3]=The Disintegration Loops III&n[3]=&m[3]=&a[4]=William Basinski&t[4]=d|p 6&i[4]=1320945279&o[4]=P&r[4]=&l[4]=2436&b[4]=The Disintegration Loops IV&n[4]=&m[4]=&a[5]=William Basinski&t[5]=d|p 1.2&i[5]=1320946592&o[5]=P&r[5]=&l[5]=1309&b[5]=The Disintegration Loops IV&n[5]=&m[5]=&a[6]=DJ Krush&t[6]=Nosferatu (feat. Mr. Lif)&i[6]=1320955824&o[6]=P&r[6]=&l[6]=225&b[6]=Jaku&n[6]=&m[6]=&a[7]=Masterminds&t[7]=No Test (feat. Mr. Lif)&i[7]=1320956370&o[7]=P&r[7]=&l[7]=242&b[7]=The Underground Railroad&n[7]=10&m[7]=
11/11/2011 14:22:18.104: Last.FM: Cache Submit URL http://post2.audioscrobbler.com:80/protocol_1.2?s=d566e8fe580e475f9f80d9976b321452&a[0]=Roy Shirley with The Caltone Studio Orchestra&t[0]=Get On The Ball&i[0]=1320704058&o[0]=P&r[0]=&l[0]=193&b[0]=Caltone R%26B TONE 101&n[0]=Caltone R&B TONE 101&m[0]=&a[1]=Czerwone Gitary&t[1]=Kwiaty We Wlosach&i[1]=1320704189&o[1]=P&r[1]=&l[1]=134&b[1]=O Milosci&n[1]=16&m[1]=&a[2]=Godfather Don&t[2]=Involuntary Excellence&i[2]=1320704471&o[2]=P&r[2]=&l[2]=284&b[2]=Hazardous&n[2]=10&m[2]=&a[3]=William Basinski&t[3]=D|P 5&i[3]=1320940735&o[3]=P&r[3]=&l[3]=3140&b[3]=The Disintegration Loops III&n[3]=&m[3]=&a[4]=William Basinski&t[4]=d|p 6&i[4]=1320945279&o[4]=P&r[4]=&l[4]=2436&b[4]=The Disintegration Loops IV&n[4]=&m[4]=&a[5]=William Basinski&t[5]=d|p 1.2&i[5]=1320946592&o[5]=P&r[5]=&l[5]=1309&b[5]=The Disintegration Loops IV&n[5]=&m[5]=&a[6]=DJ Krush&t[6]=Nosferatu (feat. Mr. Lif)&i[6]=1320955824&o[6]=P&r[6]=&l[6]=225&b[6]=Jaku&n[6]=&m[6]=&a[7]=Masterminds&t[7]=No Test (feat. Mr. Lif)&i[7]=1320956370&o[7]=P&r[7]=&l[7]=242&b[7]=The Underground Railroad&n[7]=10&m[7]=
11/11/2011 14:22:18.936: Last.FM: Cache Submit Failed Plugin bug: Not all request variables are set - got 74 parameters.
11/11/2011 14:22:18.952: Last.FM: Cache Submission Failed Plugin bug: Not all request variables are set - got 74 parameters.
11/11/2011 14:22:18.967: Last.FM: Cache add Akrobatik - Wreck Dem (with Mr. Lif)
11/11/2011 14:22:18.977: Last.FM: Cache track added Akrobatik - Wreck Dem (with Mr. Lif)[/code]